1. Field of the Invention
The present invention relates to a power-generation motor control system that is mainly mounted in a vehicle, operates as a motor when an engine starts or when it assists the torque of the engine, and can operate also as an electric power generator after the engine has started.
2. Description of the Related Art
In recent years, in order to raise gasoline mileage and conformity to the environment standard, there has been developed a vehicle that is equipped with a power-generation motor and performs a so-called idling stop in which the engine is stopped when the vehicle stops and the power-generation motor is driven so as to restart the engine when the vehicle starts. Because the power-generation motor utilized in such a vehicle as described above is required to be small-size, low-cost, and high-torque; therefore, in many cases, a magnetic-field-winding synchronous power-generation motor is utilized, as the power-generation motor (e.g., refer to Patent Document 1).
In some cases, in a magnetic-field-winding synchronous power generation motor, torque control is performed by controlling the magnetic-field current and the armature current. In this case, when the value of a driving torque command is small, the value of a magnetic-field current command at a time when driving is performed also becomes smaller than a rated value (e.g., refer to Patent Document 2).